"As we push humans out into the solar system, we're doing it internationally, and this is that first step," said Bill Gerstenmaier, head of NASA's human spaceflight programs.

Under a deal signed last month, the European Space Agency will contribute the service module supporting an unmanned Orion capsule during its first launch from Kennedy Space Center atop the heavy-lift Space Launch System rocket.

The service module provides power, propulsion and life support for Orion, which is being designed to carry up to four astronauts on trips to the moon, an asteroid or Mars.

The entire spacecraft, including the crew and service modules, a heat shield and a launch abort system, will be assembled at KSC, where the Orion contractor team remains on track to grow to 350 or 400 within a year.

Europe's service module will be based on its ATV cargo resupply vehicle, which is scheduled to make a fourth flight to the International Space Station in April.

Officials said their space station partnership had provided the experience and framework to work together on exploration missions.

"Exploration in the future, I think, will become more and more an international endeavor," said Thomas Reiter, ESA's director of human spaceflight and operations. "This is a good choice to make in order to exploit synergies developed in the past and that can be beneficial for reaching common objectives."

Europe's contribution to the late 2017 mission will be worth about $200 million, Reiter said, but that won't translate directly into savings for NASA.

The deal won't change the value of Lockheed Martin Corp.'s Orion prime contract, which is projected to reach $14.5 billion through the capsule's first crewed flight in 2021.

Rather, Gerstenmaier said, the deal would improve the overall system and allow some work to be shifted to help reach the launch targets.

"It allows us to kind of work smarter within the contracts we have to make sure we're going to get to those dates, the 2017 and 2021 date, with more robustness," he said.

The early cooperation with Europe, and potential deals with other nations, could ultimately influence the missions NASA chooses to fly, Gerstenmaier said.

For now, the 2017 and 2021 missions are expected to fly "in the vicinity of the moon."

The agreement with Europe only covers the earlier flight, known as Exploration Mission 1, but if spare parts aren't needed they could be applied to the second mission.

Meanwhile, Kennedy crews are preparing for a first launch of an unmanned Orion in 2014 atop a Delta IV Heavy rocket from Cape Canaveral Air Force Station.

Called Exploration Flight Test-1, the mission aims to loft Orion 3,600 miles above Earth to test how its heat shield handles re-entry at near the speed of a lunar return. Lockheed will provide the service module for that flight.

Mark Geyer, NASA's Orion program manager, said the agency had a plan to fix cracks in several structural ribs that occurred during November pressure tests of the first space-bound Orion.

"We're actually flying in 20 months," he said. "We're down at the Cape installing hardware as we speak, and doing software testing in Denver. So it's an exciting time for us."

Geyer said the service module deal with Europe wouldn't accelerate the 2017 mission, but that is not what mattered most.